Now the monthly Wasde, the benchmark US crop report, has passed, it is time to anticipate the next showpiece.

And that is one of macroeconomic importance, being the outcome of the Federal Reserve's monthly monetary policy meeting, which many believe this time will bring a further move to shore up the economy – namely another, third round of quantitative easing, or so-called "QE3".

"Fed chairman Ben Bernanke is expected to hold press briefing at about 18:15 GMT to announce the outcome of the Federal Open Market Committee meeting," Lynette Tan at Phillip Futures noted.

"Markets widely expect another round of bond-buying to be approved during the meeting. This will stoke further liquidity-fuelled buying of commodities."

Mixed picture

But will the Fed meet expectations? Investors were not taking too many chances in early deals.

Shares closed mixed in Asia, gaining 0.4% in Tokyo, but losing 0.5% in Sydney and 0.8% in Shanghai.

The dollar eased, but by a modest 0.1% as of 09:00 UK time (03:00 Chicago time), remaining among its lowest levels in four months.

And the volatility evident in Chicago on Wednesday after the Wasde was released, when both wheat and, especially, soybeans recovered from negative territory to close higher, gave way to something more becalmed.

To conditions much, in fact, like those 24 hours ago in the run-up to the crop report.

'Optimistic outlook'

Indeed, in some respects, it was as if the Wasde never happened.

Sure, the positive comment continued on the briefing's meaning for soybean prices, after it cut the estimate for the US crop more than investors had expected.

"The outlook for global oilseed prices remains optimistic. Extremely limited US soybean supplies means price induced demand rationing is needed to ensure inventories are not exhausted," Luke Mathews at Commonwealth Bank of Australia said.

But, with QE3 now the hot topic, soybeans for November fell back 0.5% to $17.36 ½  a bushel in Chicago, with some investors opting to take profits after the 2%-plus gains of the last session.

Corn vs sugar

That was in fact a bigger drop than for corn, over which the negative talk continued, after the Wasde introduced only a small downgrade to the US crop, rather than the 400m-bushel one investors had expected.

Richard Feltes at RJ O'Brien noted that losses in the last session meant corn futures price chart had incurred "further damage which, along with large fund long positions, suggests the potential for erosion in the December corn contract into the $7.40-a-bushel area, in the absence of dire yield reports out of western Midwest".

And then there are signs of weakened demand which appear to be extending into the US ethanol sector, whose production of the biofuel fell to a six-week low last week, and potentially into other industrial use too, as the likes of high fructose corn syrup face up to falling sugar prices.

"Potentially adding to corn processing's woes, sugar prices are trading near two-year lows as excessive supplies pressure the market," Brian Henry at Benson Quinn Commodities said.

"We could see corn-based sweeteners displaced by raw sugar, particularly in the southern markets."

'Still upside potential'

Still, he added that some uncertainty over the Wasde estimates, and particularly over an apparently low number for corn fields abandoned because of drought damage, mean "these production numbers will continue to be debated as we see yield results and the actual number of harvested acres becomes clearer".

"With questions concerning the quality of the crop and rationing that still needs to take place, there is still upside potential in this market," Mr Henry added.

CBA's Luke Mathews said: "US corn supplies still remain critically tight and prices may remain high to support ongoing demand rationing."

Corn for December fell, by 0.5% to $7.65 ½ a bushel.

'Further downgrades to occur'

That left wheat as the best performer, recording a fall of just 0.25 cents to $8.89 ¾ a bushel for Chicago's December lot, amid continued questions over some of the Wasde data for this grain too.

"Notably, the USDA retained their Australian wheat production forecast at a very large 26m tonne despite the recent deterioration in local crop conditions and Abares' revised forecast of 22.5m tonnes," Mr Mathews said.

"This implies further downgrades to the USDA's global wheat production estimate are likely to occur in the coming months."

Export dynamics

Demand offered extra fillips too. Russian wheat was noticeably absent from a tender by Jordan, which on Wednesday bought 100,000 tonnes probably of Ukrainian supplies.

And more will be known about the state of Russia's supplies later, when Gasc, Egypt's wheat authority, unveils the results of its seventh tender in a month.

The last one, on Tuesday, appeared to indicate the waning of Russian export supplies, which would herald the switching of demand to other exporters, notably the European Union and the US.

US wheat exports "remain behind the pace needed to meet USDA's expectations", Benson Quinn's Brian Henry said.

"But the US offers are getting more competitive as the prospects of the Black Sea origins leaving the export market become more prevalent."

'Subdued outlook'

Among soft commodities, cotton extended losses to what was considered a bearish Wasde report for the fibre, in lifting expectations for world supplies yet again.

"The outlook for cotton prices remains subdued. Global cotton demand has been revised lower and global cotton inventories have been revised higher to record high levels," CBA's Luke Mathews said.

New York's December contract lost 0.3% to 73.09 cents a pound.

Revival – for now

But New York raw sugar actually went further in rebounding from two-year lows, adding 0.8% to 19.87 cents a pound, on further short-covering, for now at least, encouraged by uncertainty ahead of the Fed meeting.

Mr Mathews noted that much news on the sweetener has actually been "bearish".

"For example, reports coming out of the India Kingsman conference suggested China and Russia could be absent from the [import] market in 2012-13".

Phillip Futures' Lynette Tan said: "Rapid crushing in top producer Brazil, lower demand from top consumers China and Russia, and increasing monsoon rains in India will likely to continue to weigh on sugar prices in the long term."